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The Culicoides of the subgenus Avaritia (Diptera: Ceratopogonidae) in the Palaearctic region: through unsuspected diversity with epidemiologic implications

Mathieu B., Cetre-Sossah C., Garros C., Balenghien T., Candolfi E., Delecolle J.C.. 2012. In : E-sove 2012 : from biology to integrated control in a changing world. Abstract book. Montpellier : European Society for Vector Ecology, p. 32-32. Conférence E-SOVE. 18, 2012-10-08/2012-10-11, Montpellier (France).

The biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are known vectors of pathogens especially Orbivirus of the Reoviridae family such as bluetongue, african horse sickness, epizootic hemorrhagic disease and more recently Schmallenberg viruses. The western Europe and the Mediterranean basin faced bluetongue transmission with the 6 species belonging to the Avaritia subgenus recorded in these areas including the species closely related to the Obsoletus group. To date, no study encompasses the whole number of species belonging to a subgenus at a biogeographical scale. The data presented focus on local or on country fauna scale using a classification based on subgenus and/or group of species. Among the latter, the presence of cryptic species has been pointed out by recent phylogenetic studies. These classification discrepancies between authors since decades result in a taxonomic imbroglio. Recent findings of specimens with tricky morphology related to the Obsoletus group in France led us to better describe the systematic and the taxonomy of the subgenus Avaritia in the Palaearctic region. This study focuses on investigating the phylogenetic relationships between and within the Avaritia species of the Palaeactic region with a special interest for the Obsoletus group at a world scale. Voucher specimens were selected based on morphology, sequenced for the CO1 region (mtDNA) and then slide-mounted allowing a morphological interpretation of the results afterwards. A total of 82 CO1 sequences including 43 sequences from the GenBank database were analyzed by Bayesian inference and the resulting tree was used to study species boundaries. The Barcoding gap was evaluated for the closest related species not supported by the species delimitation analysis. Within the Avaritia subgenus, we propose a new systematic scheme for the species of the Obsoletus group including C. scoticus as a basal clade with the two following complexes: the Sanguisuga complex with the species C. abchazicus, C. gornostaevae, C. sanguisuga and C. sinanoensis; the Obsoletus complex made of the species C. obsoletus, C. montanus and a new species. Culicoides filicinus, absent in this analysis, could not be placed in the proposed scheme. The existence of Dewulfi and Chiopterus complex is discussed. The results of the species boundaries analysis and the presence of discriminant morphological characters support the evidence of two new species under description with one in the Obsoletus complex. We also point out new records of C. gornostaevae (France, Sweden and Switzerland) and C. aff. sanguisuga (Sweden). The subgenus Avaritia includes worldwide major vectors of Orbivirus. The revealed diversity increases up to 10 species in western Europe and questions about the possible vector roles in Europe of these newly recorded species. Evaluating the vector role of the Avaritia species in bluetongue and other viruses transmission reaches a higher challenging level for the European teams. (Texte intégral)

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